U.S. patent application number 09/840750 was filed with the patent office on 2002-01-03 for display device.
Invention is credited to Yabuki, Masanori.
Application Number | 20020000953 09/840750 |
Document ID | / |
Family ID | 18634349 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020000953 |
Kind Code |
A1 |
Yabuki, Masanori |
January 3, 2002 |
Display device
Abstract
The object of the present invention is to provide an image
display device capable of radiating over an image formed into a
character with a uniform luminosity as a luminescent surface made
according to the dot matrix system without increasing the number of
components. To this end, the display device includes the first
luminescent section having a prescribed area and the second
luminescent section constituting a display with an area larger than
that of the first luminescent section, wherein the first and the
second luminescent sections include luminescent bodies radiating as
electrons move and a pair of electrodes sandwiching these
luminescent bodies, at least one of these electrodes determines the
luminescent area thereof, and the second luminescent section is
constituted by a plurality of divided electrodes.
Inventors: |
Yabuki, Masanori;
(Stuttgart, DE) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Family ID: |
18634349 |
Appl. No.: |
09/840750 |
Filed: |
April 23, 2001 |
Current U.S.
Class: |
345/36 |
Current CPC
Class: |
G09G 3/2011 20130101;
G09G 3/30 20130101; G09G 2320/02 20130101; G09G 3/12 20130101 |
Class at
Publication: |
345/36 |
International
Class: |
G09G 003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 25, 2000 |
JP |
2000-124177 |
Claims
What is claimed is:
1. A display device comprising: a first glass substrate; a second
glass substrate; dot matrix display formed of electroluminescent
material, said dot matrix display comprising a plurality of dot
display portions, a first plurality of electrodes connected with
said dot display portions and said first glass substrate, and a
second plurality of electrodes connected with said dot display
portions and said second glass substrate; a figure display formed
of electroluminescent material, said figure display comprising a
plurality of figure display portions, a third plurality of
electrodes connected with said figure display portions and said
first glass substrate, and a fourth plurality of electrodes
connected with said figure display portions and said second glass
substrate; wherein the area of the figure display is larger than
the area of one of said dot display portions and an area of
luminescence of each of said figure display portions is formed by
applying a one of said third plurality of electrodes and one of
said fourth plurality of electrodes to said figure display.
2. The display device of claim 1 further comprising: a drive
circuit for driving operating electrode and common-line electrodes
for supplying electric current to said plurality of dot display
portions and said plurality of figure display portions.
3. The display device of claim 1 wherein the area of each of the
figure display portions is substantially the same as the area of
the dot display portions.
4. The display device of claim 1 wherein said figure display
portions are shaped to display at least one letter and the
electrodes in the third and fourth plurality of electrodes are
separated by at least one slit.
5. The display device of claim 4 wherein said slit is formed by a
line finer than said letter.
6. The display device of claim 4 wherein said slit is aligned with
a different inclination than said letter.
7. The display device of claim 1 wherein said figure display
portions are shaped to display at least one number and the
electrodes in the third and fourth plurality of electrodes are
separated by at least one slit.
8. The display device of claim 7 wherein said slit is formed by a
line finer than said number.
9. The display device of claim 7 wherein said slit is aligned with
a different inclination than said number.
10. The display device of claim 1 wherein said dot display is
formed of organic electroluminescent material.
11. The display device of claim 1 wherein said figure display is
formed of organic electroluminescent material.
12. The display device of claim 1 wherein the area of each of said
third plurality of electrodes is the same as the area of each of
said dot display portions.
13. The display device of claim 1 wherein the area of each of said
fourth plurality of electrodes is the same as the area of each of
said dot display portions.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a display device used in
electronic equipment and for displaying various character
information and characters, in particular to a display device for
displaying pictures by using organic electroluminescent (EL)
elements in the display section.
[0003] 2. Description of Related Art
[0004] As a flat-type display device based on the dot matrix
display system, there is a display device in which luminescent
elements such as organic electroluminescent (EL) elements are used.
A luminescent element based on organic electroluminescent (EL)
elements (hereinafter referred to as "organic EL element") is an
element composed basically of a luminescent layer made of laminated
fluorescent material in which electrodes of a small work function
(electrodes for injection of electrons) are formed. Such organic EL
elements are characterized by their ability to provide a very high
luminance for a small voltage.
[0005] As shown in FIG. 6, a display device in which organic EL
element is used 21 (hereinafter referred to simply as "the display
device") has organic layers (luminescent layers) 22a and 22b
sandwiched between a plurality of common line electrodes 23 serving
as negative poles and a plurality of segment line electrodes 24
serving as positive electrodes, and disposed between the
transparent (glass) substrates 25 and 26. Any potential difference
given between the common line electrodes 23 and the segment line
electrodes 24 creates an electric field between the organic layers
22a and 22b, and electrons accelerated by this electric field
creates electron-hole pairs. Alternatively, the application of an
electric field may result in the disappearance of electron-hole
pairs. The area of the part radiating at this time (hereinafter
referred to as the "luminescent surface") will be the area of
individual electrodes for injection of electrons sandwiching the
organic layers 22a and 22b.
[0006] Display devices developed in recent years adopted the dot
matrix system for chronologically changing pictures and figures
specifically formed for each character for fixed pictures. As
figures specifically formed for each character are used for fixed
pictures, curves can be used freely and freedom of display may be
enhanced. A display device including both a display section based
on a prior dot matrix system and a display section for displaying a
figure formed into a specific character will be explained with
reference to FIGS. 6 and 7.
[0007] The display device 21 includes a dot display portion 27
based on the dot matrix system, which is connected with a line
electrode drive circuit 28 and a column electrode drive circuit 29
providing a potential difference to the organic layer 22a. Line
electrode drive circuit 28 and column electrode drive circuit 29
are connected with the control section 30. Similarly, the display
device 21 includes a figure display portion 31 for displaying a
figure formed into a character, which is connected with a line
electrode drive circuit 32 and a column electrode drive circuit 33
providing a potential difference to the organic layer 22b. The line
electrode drive circuit 32 and column electrode drive circuit 33
are connected with the control section 34. Control sections 30 and
34 are designed to receive inputs of image signals and based on
these image signals each of these control sections 30 and 34
control the line electrode drive circuits 28 and 32 and column
electrode drive circuits 29 and 33 to change the potential
differences given to the organic layers 22a and 22b of the dot
display portion 27 and the figure display portion 31.
[0008] In case where the dot matrix system is used for displaying
any picture, the reduction of each dot or radiating surface to a
small area produces clearer pictures. On the other hand, where a
figure formed into a specific character is to be displayed, the
enlargement of the figure itself for display makes it easier to
view. Thus, a figure formed into a character tends to grow far
larger than a dot adopted for the dot matrix system. In other
words, the area of electrodes into which electrons are injected to
radiate a figure formed into a character on the organic layer 22b
grows larger than the area of an electrode into which electrons are
injected to radiate according to the dot matrix system. Therefore,
even if the same potential difference is given to both of the
organic layers 22a and 22b, the amount of electric current flowing
into the latter organic layer 22b grows smaller. As a result, in
comparison with the luminescent area of each dot according to the
dot matrix system, the luminescent surface of the figure formed
into a character grows darker.
[0009] For the above reason, in order to maintain the luminosity of
the luminescent surface of the figure formed into a character at a
level of luminosity similar to that of the luminescent surface of
each dot displayed according to the dot matrix system, the
potential difference between the common line electrodes and the
segment line electrodes must be kept at a higher level than the
potential difference applied to the organic layer 22a radiating
according to the dot matrix system. Therefore, apart from the
common line electrodes, the segment line electrodes, the line
electrode drive circuit and the column electrode drive circuit for
supplying electric current to the organic layer 22a radiating
according to the dot matrix system, new common line electrodes,
segment line electrodes, line electrode drive circuit and column
electrode drive circuit must be created to provide for further
potential difference, which resulted in additional components,
further complication of the control section and added up the
cost.
SUMMARY OF THE INVENTION
[0010] It is therefore an object of the present invention to
provide a display device by which a figure formed into a character
can radiate with an even luminosity as that of the luminescent
surface according to the dot matrix system without increasing the
number of components.
[0011] In order to solve the above problem, the display device
according to one embodiment of the present invention includes the
first luminescent section of a prescribed area and the second
luminescent section forming a picture of an area larger than the
first luminescent section, the first and the second luminescent
sections being formed by a luminescent body radiating as electrons
move and a pair of electrodes sandwiching this luminescent body, at
least one of the electrodes determining the area of radiation, and
at least the second luminescent section being formed by a plurality
of divided electrodes.
[0012] In another embodiment, the display device according to the
present invention includes a drive circuit for driving the segment
line electrodes and common line electrodes for supplying electric
current to the first luminescent section, and the drive circuit
drives the second luminescent section.
[0013] In still another embodiment, the display device according to
the present invention includes electrodes forming the second
luminescent section divided so that each of them would take the
same area as that of the first luminescent section.
[0014] In still another embodiment, the present invention provides
a display device in which the electrodes of the second luminescent
section are disposed in such a way as to form at least a character
and the electrodes are divided by slits crossing with
characters.
[0015] In another embodiment, the present invention provides a
display device in which slits are formed by a line smaller than
characters.
[0016] The presently preferred embodiment includes a first
luminescent section of a prescribed area, i.e. a dot of the dot
display portion 2, and a second luminescent section displaying a
figure of an area larger than that of said first luminescent
section, i.e. a figure display portion 3. As electrons move between
the pair of electrodes sandwiching the first or second luminescent
sections, the luminescent body radiates. The area of luminescence
is determined by at least one of the electrodes. If the electrode
of the second luminescent section is divided into a plurality of
electrodes such that the area of each divided subsection of the
second luminescent section becomes close to that of the first
luminescent section, the luminosity of the second luminescent
section can be brought to the same level of luminosity as that of
the first luminescent section even if the same potential difference
is applied.
[0017] By including a drive circuit for driving the segment line
electrodes and the common line electrodes for supplying electric
current to the first luminescent section and the use of this drive
circuit to drive the second luminescent section, the display device
according to the present invention can better apply a potential
difference to the second luminescent section without increasing the
number of components.
[0018] By utilizing a plurality of electrodes in the second
luminescent section in order to provide luminescent subsections
with an area substantially the same as the area of the first
luminescent section, the display device according to the present
invention can more accurately radiate the first and the second
luminescent sections with an even luminosity by applying a similar
potential difference to them.
[0019] By forming electrodes of the second luminescent section as
slits which cross with the display characters, the display device
according to the present invention enhances a user's ability to
distinguish lines constituting characters from slits even when the
second luminescent section contains characters. Thus, visual
recognizability is not impaired.
[0020] Further, the electrodes of the second luminescent section
may be constructed with a width substantially smaller than the
width of the lines constituting characters. This also reduces the
likelihood of impaired visual recognizability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] FIG. 1 is a schematic block diagram showing the
interconnection of one embodiment of the display device of the
present invention.
[0022] FIG. 2 is a schematic illustration of the dot display
portion of the display device according to one embodiment of the
present invention.
[0023] FIG. 3 is a schematic sectional view of the display device
according to one embodiment of the present invention.
[0024] FIG. 4 is a schematic illustration of the figure display
portion according to a first embodiment of the present
invention.
[0025] FIG. 5 is a perspective view showing the figure display
portion according to a second embodiment of the present
invention.
[0026] FIG. 6 is a sectional view of a prior display device.
[0027] FIG. 7 is a schematic block diagram showing the
interconnection of a prior display device.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Referring to FIGS. 1 to 5, preferred embodiments of the
present invention will be explained. Incidentally, FIG. 1 is a
schematic block diagram showing the interconnection of the display
device according to one embodiment of the present invention, FIG. 2
is a schematic illustration of the dot display portion of the
display device according to one embodiment of the present
invention, FIG. 3 is a schematic sectional view of the display
device according to one embodiment of the present invention, FIG. 4
is a schematic illustration of the figure display portion according
to a first embodiment of the present invention, and FIG. 5 is a
perspective view showing the figure display portion according to a
second embodiment of the present invention.
[0029] As shown in FIG. 1, a display device 1 according to one
embodiment of the present invention includes a dot display portion
2 for displaying according to the dot matrix system and a figure
display portion 3 for displaying a figure formed into a character.
The display device 1 is connected with a line electrode drive
circuit 5 and a column electrode drive circuit 6 for applying a
potential difference to each of organic layers 4a and 4b of the dot
display portion 2 and the figure display portion 3. And the line
electrode drive circuit 5 and the column electrode drive circuit 6
are connected with a controller 7.
[0030] The controller 7 is designed to control the line electrode
drive circuit 5 and the column electrode drive circuit 6 so that
the line electrode drive circuit 5 and the column electrode drive
circuit 6 may cause changes in the potential difference applied to
each of the organic layers 4a and 4b of the dot display portion 2
and the figure display portion 3. Image signals are to be inputted
thereto for this purpose.
[0031] Then, as shown in FIG. 2, the dot display portion 2 includes
an organic layer 4a, a plurality of common line electrodes serving
as negative electrodes 8, a plurality of segment line electrodes
serving as positive electrodes 9, the organic layer 4a being
sandwiched between the common line electrodes 8 and the segment
line electrodes 9 and disposed furthermore between transparent
(glass) substrates 10 and 11. The dot display portion 2, the common
line electrodes 8 are connected with the line electrode drive
circuit 5 through their connecting line 12 and the segment line
electrodes 9 are connected with the column electrode drive circuit
6 through their connecting line 13. In addition, as shown in FIG.
3, the common line electrodes 8 are disposed on the lower surface
of the glass substrate 10 in parallel each other, and segment line
electrodes 9 are disposed on the upper surface of the glass
substrate 11 in parallel each other and in the vertical direction
to the common line electrodes 8.
[0032] The application of a potential difference between the common
line electrodes 8 and the segment line electrodes 9 by the
operation of the line electrode drive circuit 5 and the column line
electrode drive circuit 6 generates an electric field on the
organic layer 4a, and electrons accelerated by this electric field
generates electron-hole pairs, or electrons at the center of
radiation are excited resulting in the disappearance of
electron-hole pairs when electrons returns to their normal state
from a state of excitation. The area of luminescent section at this
time will be the area of a section where individual common line
electrode 8 and segment line electrode 9 crosses sandwiching the
organic layer 4a (electrodes subject to the injection of
electrons).
[0033] As shown in FIGS. 2 and 4, the figure display portion 3
includes an organic layer 4b, common-line electrodes 14 and
segment-line electrodes 15, the organic layer 4b being sandwiched
between the common-line electrodes 14 and the segment-line
electrodes 15, and disposed furthermore between the glass
substrates 10 and 11. In addition, the common-line electrodes 14
and the segment-line electrodes 15 are respectively disposed on the
glass substrates 10 and 11, and the common-line electrodes 14 and
the segment-line electrodes 15 facing each other on the opposite
sides have identical shapes. The common-line electrodes 14 are
divided by a plurality of slits 16 into a plurality of common-line
electrodes 17, 18, 19 and 20. Similarly, the segment-line
electrodes 15 are divided by a plurality of slits 21 into a
plurality of segment-line electrodes 22, 23, 24 and 25. These
divided common-line electrodes 17, 18, 19 and 20 and segment-line
electrodes 22, 23, 24 and 25 are disposed in such a way that the
electrodes facing each other on the opposite sides, for example
common-line electrodes 17 and segment-line electrodes 22, have
identical shapes and identical areas.
[0034] Each of the common-line electrodes 17, 18, 19 and 20 and
each of the segment-line electrodes 22, 23, 24 and 25 are divided
by the slits 16 and 21 in such a way that each electrode would have
more or less the same area, and their respective area is more or
less the same area as a display area of the dot display portion 2.
Therefore, it is possible to obtain the same luminosity by applying
to the organic layer 4b a potential difference equal to that
applied by the column electrode drive circuit 5 and the line
electrode drive circuit 6 to the dot display portion 2.
[0035] The common-line electrodes 14 and the segment-line
electrodes 15 are respectively connected with the coupling lines 12
and 13, and the application of a potential difference by the column
electrode drive circuit 5 and the line electrode drive circuit 6
between each of the common-line electrodes 17,18,19 and 20 and each
of the segment-line electrodes 22, 23, 24 and 25 generates an
electric field on the organic layer 4b, and electrons accelerated
by this electric field generates electron-hole pairs, or excites
electrons at the center of luminescence resulting in the
disappearance of the electron-hole pairs or luminescence when the
electrons returns from an excited state to the normal state. At
this time, the area of the luminescent section will be identical or
equal to the area of individual common-line electrode 17, 18, 19,
20 or that of individual segment-line electrode 22, 23, 24 or 25
sandwiching the organic layer 4b.
[0036] In the second embodiment of the present invention, a display
created in the form of a character contains, as shown in FIG. 5,
alphabets and other letters 26. And the slit 16 is provided in
order to prevent that lines constituting the letter "A" from having
the same inclination as the slit. Thus, when the display created as
a character contains letters, the setting of a different
inclination of the slit 16 from that of the line constituting said
letters enables a viewer to distinguish the line constituting the
letters and therefore maintains visual recognizability. Further,
the choice of a narrower width of the slit than that of the line
constituting said letter also avoids impairing the visual
recognizability of the lines constituting letters contained in a
picture formed as a characters. Incidentally, in this second
embodiment, the other elements are the same as those of the first
mode of carrying out and therefore explanations thereon are
omitted.
[0037] It is to be understood that a wide range of changes and
modifications to the embodiments described above will be apparent
to those skilled in the art and are contemplated. It is therefore
intended that the foregoing detailed description be regarded as
illustrative, rather than limiting, and that it be understood that
it is the following claims, including all equivalents, that are
intended to define the spirit and scope of the invention.
* * * * *